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Somebody at AA asked about the difference between electromagnets and perm magnet. Thankfully the AA idiots who pick the pieces of brain at my site and already learned that the idiotic blabbering about “the electromagnets have more flux” is completely out of picture. Now they come up with more refines explanations. Still, I feel that it is off the mark.

Somebody Al Sekela posted a reply that I found worth to comment upon:

http://www.audioasylum.com/forums/hug/messages/14/143034.html

 I composed a reply, that of was deleted from AA, but I did not truly intend to post it in the AA sewers to rather to advanced the concept at my site. Her is the deleted post:

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I am glad that after the years of foolish drooling and proclaiming faulty idiotic statements the AA people gained some more or less common sense and look at the electromagnets more rational then just brainless glorification. Still, there is a lot of wrong in what people sell to themselves about electromagnets. In what Al Sekela said I see some inconsistencies that I would like to comment upon. I am glad that you do not sound as a Moronic industry whore, (there are some voices in this thread that do), so I would extend to you some credibility and integrity.

Al Sekela wrote:

Permanent magnets are not ideal. When used for speaker motors, their magnetic fields may respond to the fields created by the signal currents in the voice coils. This response may have some granularity, depending on the magnetic domain properties of the motor. The result is a subtle distortion that increases in fraction of the signal as the signal decreases in level. This kind of distortion gives a mechanical character to the sound, especially in well-recorded natural music, where the decay into silence has musical significance. This kind of distortion limits the resolving ability of the speaker.

To the problems flux modulations the permanent magnets driver and electromagnets are exposed equally, In fact if you look more carefully then you might observe that electromagnets sink flux faster then permanent magnets of the same magnetic density.  So, if you explain the less granular decay by electromagnet driver (and I partially agree with you) then it might not be explained by “fields created by the signal currents in the voice coils”.  It shall be something else. Also, let have some perspective about it. If we deal with Cogent-like MF drivers that are 500Hz and up and if it has 110dB sensitively then to develop let say 90dB it needed 50mV. If the driver runs at 1.8T then the 50mV in the voice coil generate the field that is absolutely negligible it relation to 18.000 Ga. So, the explanation of the flux modulations and contra-modulations I feel are very inappropriate. It is not bass driver but FM.  BTW, if you did experiments with use of  bass drivers and electromagnets then you might know that  electromagnets have very questionable advantage in lower frequency.

Al Sekela wrote:

Two other areas in audio have similar problems. Push-pull output stages suffer from what is called "crossover distortion." The tube or transistor amplifier characteristics change as the signal approaches zero. A band-aid is to increase the bias, so most power amplifiers are called "Class A-B," with both sides of the push-pull topology conducting current at zero signal. A true Class B amplifier would allow each side to go into cutoff (no current) exactly at zero signal. A true Class A amplifier never cuts the output devices off, and is very inefficient. However, many audiophiles prefer this type because it avoids crossover distortion. Single-Ended Triode (SET) amplifiers avoid the problem completely because the output device does not get close to zero except at maximum signal.

And how the electromagnet driver deal with crossover distortions better then permanent magnets? It is not to mention that people who run MF with PP amps are a bit … wrong, unless it is a ceramic magnet with hard suspension (that would be totally different subject)

Al Sekela wrote:

Tube amplifier output transformers also have grain that depends on the core material. Different choices for core material give different tradeoffs in distortion verses ability to handle large bass levels, efficiency, and cost. The tradeoffs are so severe that some folks use so-called Output Transformer-Less (OTL) tube power amps, such as the Atma-Sphere amps. These amps are entirely free of the transformer grain problem and are capable of superb resolution.

Sorry, it is absolutely wrong and you might to educate youssef a bit deeper about the harmonic problems of OTL amps. BTW, do not use AtmaSphere as it is a very bad example of OTL amps. Also, there is no conflict in SET between “grain” and ability to handle large bass levels – you looks like confided about it.  Still, if to accept that what you propose is accurate then what it has to do with the subject of electromagnets drivers and their alleged advantage over perm magnet?

Al Sekela wrote:

Good reproduction requires the audio equipment to work well at the extremes of maximum and minimum signal as well as at average signal levels. Field coil speakers have an advantage over permanent magnet motor speakers at low signal levels. Whether they perform well at high levels depends on other design choices that are common with permanent magnet motor speakers.

Ok, you feel that a permanent magnet motor has an advantage at minimum signal then can you propose an explanation why you feel so and how can one verify it? I am not sure that I agree with it, I do not disagree either. I am not sure that you have a right explanation and I am not sure that it leads to a right concussion. I have mine explanation but I would hold my view until you indicate that we at least talking about the same thing.

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